Used fleet/lease car values at BCA increased by 1.3% in September to rise above £10,000 for the first time on record.
Values in the fleet and lease sector climbed by £127 (1.3%) in September compared to August, to reach £10,017.
Retained value against original MRP (manufacturers' retail price) improved to 42.65 in September from 41.7% in August.
Year-on-year values were up by £317 (3.2%), with age falling by one month and mileage down by 3,000.
The remarketing company's latest Pulse report found the headline average value of a used car rose by £34 to £8,376, the third month in a row a new record value has been established.
Year-on-year, the headline figure was up by £674, equivalent to an 8.7% increase in average values.
Average dealer part-exchange values rose by £64 to a new highpoint of £4,553. Nearly new-values also improved during September.
Simon Henstock, chief operating officer UK remarketing at BCA, said: “September saw demand keeping pace with supply, with both the auction halls and online channels being very busy.
"Sale conversion rates were high, typically exceeding 80% during September, meaning there was good churn in the marketplace.
“However, by mid-October our dealer customers were anecdotally saying that retail demand was softening and that will inevitably impact the wholesale sector.
"Professional buyers will inevitably become more choosy, cherry-picking the best presented and most attractive cars.
"It is critical to appraise and value vehicles appropriately and in line with condition, and invest in the appropriate level of preparation to attract the buyers’ attention where necessary.”